Figure 3.

Model for the role of microRNAs in the regulation of ‘tumor suppressor’ pathways in Drosophila. The miRNA bantam is a key target of the transcriptional regulator Yorkie. Yorkie is under tight control of the Hippo pathway that consists of merlin and expanded at the membrane integrating signals from an unknown transmembrane receptor. In certain cell types in Drosophila, expanded mRNA is regulated by miR-278. Warts and Mats transduce the signal from Merlin/Expanded and Hippo/Salvador. Warts and Mats are also elements of Fat/Dachsous signaling (another Drosophila tumor suppressor pathway) through Dachs. Fat also can interfere with canonical Wnt signaling and activate noncanonical Wnt signaling. This could theoretically occur via the inactivation of Yorkie and Bantam: one of Bantam's target mRNAs is Hid, which has been shown to inhibit canonical Wnt signaling.